The present invention relates to an implantable hernia repair prosthesis for reinforcing and repairing damaged tissue or muscle walls and methods for making same.
Various prosthetic mesh materials have been proposed to reinforce the abdominal wall and to close abdominal wall defects utilizing different repair prostheses and methods of installation. The methods of executing a surgical repair can be segregated into two main approaches. The repair can be made exclusively from the anterior side (closest to the surgeon) of the defect by dissecting the sac free of the fascia and pressing it back into the pre-peritoneal space and providing permanent closure of the defect. The closure can be provided through the application of space filling prostheses and overlay patches (tension-free techniques) or can be accomplished through the use of sutures (tension techniques).
An example of a tension free anterior repair is to fold a sheet of surgical mesh fabric into a multi-layer cone configuration and then to insert the mesh plug into a hernia defect to occlude the void. Such a multi-layer prosthesis is inherently stiff, may not fully conform to variations in the contour of the defect, and is subject to shrinkage that potentially could lead to recurrent herniation. The stiff, multi-layered mesh plug also may be susceptible to kinking and buckling during placement.
U.S. Pat. No. 5,356,432, discloses an implantable prosthesis that is a conical plug formed of a knitted polypropylene monofilament mesh fabric. Longitudinal pleats are hot molded into the mesh body to enhance the flexibility of the conical implant, ideally allowing the implant to closely match the contour of the herniated opening when compressed within the defect. When the device is installed into a fascial defect, the tip of the conical shaped plug presses into and against the visceral sac, potentially enabling long-term erosion of the peritoneum and underlying viscera. The device, in one embodiment, has filler material incorporated into the interior of the formed mesh cone in an attempt to minimize contraction of the device during healing. As collagen scar tissue grows into the prosthetic material, the cross linking of the maturing collagen fibers causes the scar tissue (and encapsulated plug device) to contract. This contraction of scar tissue within the defect and plug causes the surrounding diseased tissue to be subjected to tension, thus enabling re-occurrence of the hernia along the edge of the conical plug. The use of the device requires the passage of a pre-expanded plug through the hernia defect and relies upon the radial expansion force of the single layer mesh cone and filler leaves to occlude the defect. Additionally, since the plug is secured in position by anchoring to the surrounding diseased tissue, the device may dislodge and migrate within the pre-peritoneal space.
Alternatively, a defect may be repaired through the use of posterior approaches that provide various prosthetic devices in the pre-peritoneal space to prevent the peritoneum from entering the fascial defect. These devices, in some cases, require the use of laparoscopic techniques and, in other cases, require the application of the prosthesis from a remote location under the defect to be repaired. Examples of posterior approaches are disclosed in U.S. Pat. Nos. 5,116,357, 5,254,133 and 5,916,225. However, in many cases, procedures utilizing such devices are complicated, in addition to requiring the use of general anesthesia and costly disposable instrumentation to support the laparoscopic surgery.
Accordingly, the prior art lacks an implantable hernia repair prosthesis for occluding and repairing damaged muscle and tissue wall ruptures, that is adaptable to irregularities in the shape of the defect, is simple to install, does not require the use of general anesthesia during installation and resists radial collapse due to tissue incorporation.
The limitations of prior art hernia prostheses are overcome by the present invention which includes a hernia repair prosthesis having an occlusive member for aiding in the occlusion of a defect in fascia tissue. The occlusive member is convertible from a first configuration with a first axial length and a first major radial extent to a second configuration with a second axial length and a second major radial extent. The second axial length is less than the first axial length and the second major radial extent is larger than the first major radial extent. The occlusive member has a pair of subsections, each having an apex and each flaring outwardly therefrom towards a terminal end. The apexes are disposed at opposite ends of the occlusive member with the terminal ends overlapping. The pair of subsections are conjoined proximate the overlapping terminal ends.
In accordance with a method for forming the subsections, a surgical fabric is thermoset on a male die and may be stretched or heat shrunk to aid in conforming the surgical fabric to the contours of the male die.